| Injury,inflammation and tumor in maxillofacial region usually lead to various kinds of bone defects,of which some may even suffer from facial deformity,thus throwing bad effects on patients' life quality and mental health.At present,autogenous bone,allograft bone and Heterologous bone meal are the most commonly used in repairing jaw.However,due to the limited bone source,immunological rejection and infection,metal biomaterials are becoming increasingly important in bonerepairing.Currently,titanium and titanium alloy are the most widely used metal materials in bone repair,but they are less porous and have small coefficient of friction,which can be overcome by porous tantalum.We have previously proved that porous tantalum particles can lead to bone inducing and bone shaping,which has a great effect on maxillofacial bone repairing as well as the potential to become a new implant material to replace titanium.But the simple porous tantalum particles cannot provide bone growth factors and porous tantalum implant material cannot induce vascular.It has been proved that Transforming growth factor-?1(TGF-?1)can stimulate the growth of bone trabecula and microvascular.But TGF-?1 easily diffuses and resolves in vivo,which makes it unable to play a role constantly in target cells.Stable Mechanical capacity and high porosity of porous tantalum make it ideal vector of TGF-?1.Therefore,we combine TGF-?1 and porous tantalum particles,developing them into a new bioactive porous tantalum material,which is more compatible,easy to sterilize,non immunogenicity,and has strong adsorption capacity and mechanical strength,good in bone inducing and shaping.This project studies the bioactivity of this material by observing the areas of regenerated bone in bone defect regions and new microvascular density of different times and groups,thus providing basis for applying porous tantalum in clinic.Aim of researchThe aim of our research is to provide experimental evidences for repairing maxillofacial bone defect that is caused by plant peripheral inflammation by combining TGF-?1 and porous tantalum particles,improving the micro environment of maxillofacial bone,accelerating healing and enhancing the bone quality.Research MethodsSix 12-month-old male beagles were chosen as the subjects,whose first to fourth premolars of both sides were pulled out.After normal healing,a model of cylindrical bone defect was built.Three groups were involved: one was the group adopting pure porous tantalum particles as repair material(Porous Tantalum Group);one adopted porous tantalum treated by TGF-?1(Composite Group);and the non-treated group(Blank Group).Ten days before the operation,tetracycline fluorescence radioactive labeling was conducted.Two beagles were sacrificed respectively at day 30,60 and 90.The experiment specimen went through visual inspection,X-ray detection,tetracycline immunofluorescence labeling,VIII factor related antigen-antibody marker staining,toluidine blue staining,CD31 related antigen-antibody staining and sirius red stain.Results1.According to the visual study,the beagles grew well and the wound healed well after the operation.No inflammation such as suppuration was found before the experiment specimen was collected.X-ray detection found a good coupling between the porous tantalum particles and the bone tissues around;besides,in the experimental group,the porous tantalum particles were covered by new bone tissues.2.Toluidine blue staining indicated that new bone tissues could grow around and into the porous tantalum particles.At day 30,the composite group combined better with the bones around than the porous tantalum group;at day 60,trabecular bone and bone pit were found in the experimental group,but in the control group,immature blue staining bones still existed in large amount;for the blank group,blue staining area was very little at day 30,60 and 90.3.Tetracycline fluorescence showed at day 30 the area of new bone in the experimental group was larger than in the control group and the blank control group besides,the largest new bone area in which the porous tantalum particles grew into was found in the experimental group.In both the experimental group and the control group,yellow-greenfluorescence bands were found extending to the porous tantalum particles,and in the center of which,the bright yellow-green fluorescence was seen feather-shaped.4.Both VIII and CD31 indicted at day 30 larger number of the newly formed micro vessels was found in the combined group than in the other two groups.At day 60,the largest number of the newly formed micro vessels was found in the porous tantalum group.CD31 related antigen-antibody staining showed blood vessels could grow into porous tantalum particles as to the depth of 76?m.5.Results: At day 30,there were larger area of new bone and greater vnumber of the newly formed micro vessels in the combined group than in the porous tantalum group.There was an obvious difference(P<0.05);At day 60,situation reversed(P<0.05);At day 90,no significant difference was found.Conclusion1.Bone tissues and porous tantalum particles are perforating bound and the former can grow into the latter.2.Bone-formation and blood vessels-formation in early time are under the best circumstance,which shows the composites combined by TGF-?1 and porous tantalum particles can greatly facilitate bone-formation and shorten the time for healing bone defects,thus advancing the combination of porous tantalum and the tissues around.3.Blood vessels could grow into porous tantalum particles as to the depth of 76?m. |
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